Book Image

Learning RxJava

By : Thomas Nield
Book Image

Learning RxJava

By: Thomas Nield

Overview of this book

RxJava is a library for composing asynchronous and event-based programs using Observable sequences for the JVM, allowing developers to build robust applications in less time. Learning RxJava addresses all the fundamentals of reactive programming to help readers write reactive code, as well as teach them an effective approach to designing and implementing reactive libraries and applications. Starting with a brief introduction to reactive programming concepts, there is an overview of Observables and Observers, the core components of RxJava, and how to combine different streams of data and events together. You will also learn simpler ways to achieve concurrency and remain highly performant, with no need for synchronization. Later on, we will leverage backpressure and other strategies to cope with rapidly-producing sources to prevent bottlenecks in your application. After covering custom operators, testing, and debugging, the book dives into hands-on examples using RxJava on Android as well as Kotlin.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
Acknowledgements
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Tuples and data classes


Kotlin supports Tuples to a small degree, but it also offers something even better with data classes. We will look at both of these in an RxJava context.

Kotlin supports the quick creation of a Pair containing two items (which can be of differing types). This is a simple two-value, but statically-typed, tuple. You can construct one quickly by putting the to keyword between two values. This is helpful in doing zip() operations between two streams, and you just want to pair the two items together.

In the following code, we zip a stream of string items with a stream of Int items and put each pair into Pair<String,Int>.

import io.reactivex.Observable
import io.reactivex.rxkotlin.Observables

 fun main(args: Array<String>) {

     val strings = Observable.just("Alpha", "Beta", "Gamma",
     "Delta")
     val numbers = Observable.range(1,4)

//Emits Pair<String,Int>
     Observables.zip(strings, numbers) { s, n -> s to n }
             .subscribe {
 ...